Dehydration of gases containing acetylene and removal of acetylene therefrom



Feb'. 3, 1959 R. c. scoFn-:LD

DEHYDRATION 0F GASES CONTAINING A 2,871,979 CETYLENE Filed June 23',1955 AND REMOVAL OF ACETYLENE THEREFROM 2 Sheets-Sheet 1 Feb. 3, 1959SCOFIELD DEHYDRATION OF GASES CONTAINING ACETYLENE AND REMOVAL 0FACETYLENE THEREFROM 2 Sheets-Sheet 2 Filed June 23, 1955 INVENTOR. R CSCOFIELD AT ORNEYQ United States Patent AOV DEHYDRATION OF GASESCONTAINING ACETY- LEE AND REMOVAL OF ACETYLENE THERE- FR M Raymond C.Scofield, Bartlesville, Okla., assignor to Phillips Petroleum ICompany,a corporation of Delaware Application June 23, 1955, Serial No. 517,495

Claims. (ci. iss- 4115) Y This invention relates to the dehydration ofhydrocarbon gases. In onerof its aspects the invention relates to theremoval of water from a gas containinghydrocarbons including acetyleneemploying dirnethylformamide as a selective dehydrating solvent. Inanother of its aspects, the invention relates to several advantageousmodus operandi for the dehydration of a ga's containing hydrocarbonsincluding acetylene and the removal of acetylene from the dehydratedgasesobtained employing dimethylformamide in said dehydration andacetylene removal steps. Other aspects of the invention are apparentfrom a perusal of this disclosure, the drawings and the appended claims.

The removal of water from gases such 'as cracked hydrocarbon gases priorto removal of acetylene therefrom at low temperatures presents a problemwhen such dehydrating solvents or agents as glycols are employed.Indeed, the drying of the gases `is never-l as complete as can beobtained with bauxite or silica gel from which, of course, theeconomical recovery of `thehydrocarlons which would become absorbedwould present 4still Vfurther problems. Glycols are disadvantageousprincipally because of their high viscosities, about 40 centipoises at75 F. This indication is found also in the art.`

Drying by means of a silica gel or bauxite is disadvantageous because acyclic operation is required. Even more serious is the problem ofthepersistent liydrocarfbon fog produced in the acetylene-formingreaction. This fog deposits as a Vtar on the silica gel or' bauxite,interfering with drying and in `some instances .causing plugi t ging. Asa result these desiccants must be replaced frequently. v

Thus it is clear that `a `dehydrating solvent, especially adapted for`the dehydration of hydrocarbon-containing gases, `including acetylene,has remained to be found.

It is an object of this invention to provide a method for thedehydration of gases containing' hydrocarbons fincluding acetylene. f

It is another object of this invention to provide amethod for theremoval of water from hydrocarbon gases t containing acetylene followingwhich the dehydrated gases are treated -to remove acetylene. therefrom.

Other objects, aswell as the several advantages vof this invention, areapparent from a study'ofthis disclosure, the drawings and the appendedclaims;

According to this invention it hasbeen` found that dimethylformamide isideally suitedto drying operations for producing exceptionally low'dewpoints or quantitative removal of water from gases containinghydrocarbons'in- 2,871,979 Patented Feb. 3, 1959 lCC cluding acetylene.Thus, according to the invention, such a gas is contacted withdimethylformamide under conditions such that after a desired contactingthe dimethylformamide will contain sufficient water to avoid dissolvinginto or retaining in the dimethylformamide undesired quantities of thesaid hydrocarbons especially acetylene. Also according to the inventionthere are provided modus operandi in which dimethylformamide is employedfirst to dehydrate a gas following which it is employed to removeacetylene therefrom. In one `embodiment of the invention which is nowpreferred, the dimethylformamide solvent is employed at a low temepera'ture of the order of 0 F. or below to effect dehydration. Thus, ithas been found that an equimolar mixture of dimethylformamide and Waterhas a freezing point of approximately 68 Ffandthat such a mixture atsaid low temperature will be effective to dehydrate a Ihydrocarboncontaining gas, especially a gas also con# tainingacetyleneand/ or ethylene'.

It-is a feature of the present invention that the. dimethylformamide iscontacted with the gases until its water content, taking intoV account`the proportionlof solvent to the gas employed, is sufficiently high toprevent removal from the dehydration zone dissolved in the solvent anysubstantial or undesirably high proportion of. said gases, especiallyacetylene and/or ethylene.

The drawings illustrate in simplified manner ow plans of embodiments ofthe present invention. Only sulf .cient pieces of various types ofequipment such as vessels, pipes, pumps, exchangers and valves, havebeen shown to permit a ,ready understandingof the several embodimentsand how these may be varied by one skilled vin the art having studiedthis disclosure, drawing and claims. Figure l shows the flow plan of adrying operation in which an acetylene-rich dimethylformamide, whichcan' be from an acetylene absorber in which it has been used to absorbacetylene from gases containing the same, in this case a gasalsocontaining ethylene, is contacted with a gas containing acetyleneand ethylene and water underconditions and ina manner to remove,ktherefrom Vsubstantially all of th'ewater. It will be noted that in thisembodiment the dimethylformamide serves the dual function of drying thegases Iand removing acetylene therefrom.. Figure 2 shows an embodimentin which the dimethylformar'nide in the water Vremoval -zone orabsoirber is not use'ddirectly from `an acetylene'abso-rption Vandrdoesnot contain acetylene.' Thus, as later described, the dimethylformamidein the embodimentof Figurel is contacted with thegas `stream containingacetylene, ethylene and othergases, later identied, under condi,- t'ionsand in a manner `to remove substantially only water therefrom. A V Y, jReferring howto Figure 1,(a gas containing acetylene, and generallyhaving the compositions shown in lcolurrrn l of Table I, obtained fromarquench system :at a temperature of approximately is passed by way ofpipe 1, cooler 2, and pipe 3 into drying tower 4. Preferably, as amodification, a portion of dimethylformamide solvent is cooled andremoved from tray Sand vpassed by Way of pipe 6 intoadrnixture withthevgas in pipe 1. This preniixing of dimethylformamide solventrwith gasstream in pipe 1 followed by-heat Vexchange is considered,

a feature of the process, the eiciency of which is considerably improvedthereby. Drying tower 4 is constructed in any desired manner andpreferably contains contact surface supplying materials such as battles,rings, beads, etc., to cause intimate contact of the gases fed theretowith acetylene-rich dimethylformamide fed thereto by way of pipe 7. Inthis example, the acetylene-rich dimethylformamide solvent containssubstantially no water (see Table I, column 8) but does containappreciable quantities of other gases, notably carbon dioxide, vinylacetylene, and other gases as noted in Table I. The temperature of thisstream is maintained at about -20 F. The proportion of theacetylene-rich solvent fed to tower 4 is determined mainly by the amountof water in feed stream 1 since the acetylene-rich stream is essentiallya dry one. It will be noted from columns 8 and 9 of Table I that a totalof 97,482 mols per stream day of acetylene-rich solvent are removed fromthe acetylene absorber (not shown) and that of this amount of solvent,only 22,843 mols per stream day are passed into absorber 4, theremainder being passed directly by way of pipe 8 to an acetylenestripper also not shown. Upon contact in the absorber with theacetylene-containing stream fed thereto by way of pipe 3, theacetylene-rich solvent removes substantially all of the water originallycontained in said acetylenecontaining stream so that there is taken olfoverhead from the absorber 4 by Way of pipe 9 a gas stream containing noappreciable amount of water but containing substantially all of itsother components. Indeed, comparison of the acetylene values in columns1 and 7 of Table I will show an increase of the acetylene in the gas inpipe 9 over the acetylene in the gas in pipe 3. The solvent removed fromabsorber 4 by way of pipe 10 contains substantially all of the waterentering absorber 4 by way of pipe 3 and about 100 mols per stream dayof acetylene (amounting to 0.37 mol percent of the solvent) as well asother gases as evident from column 3 of Table I. This stream which is atapproximately 100 F., enters wet solvent accumulator 11 which isprovided with a packed tower 12 to which there is fed by way of pipe 13a quantity of cooling water suicient to scrub out traces ofdimethylformamide which may be entrained with gases passing fromaccumulator 11, and tower 12, by way of pipe 14 and steam jet 15 to thequench system. It is noted that the acetylene and ethylene and othergases which leave by way of pipe 14 are returned to the system and are,therefore, not lost. In absorber 4, a pressure slightly aboveatmospheric, in this embodiment 17.2 pounds per square inch absolute, ismaintained. However, the pressure in wet solvent accumulator 11 is quitelow and is of the order of 65 mm. of mercury. Liquid from wet solventaccumulator 11 is withdrawn by pipe 32 and pumped by pump 33, pipe 34 byWay of heat exchanger 35, and pipe 16 into water stripper 17. Instripper 17, water is stripped from the solvent taken overhead by way ofpipe 18, cooler 19, pipe 20 and reflux drum 21 into and out through pipe22. Pipe 22 is equipped with steam jet 23, the effluent of which isvented. The composition of the overhead from reux drum 21 is shown incolumn 5 of Table I. It will be noted that this effluent containssubstantially all of the diacetylene and, therefore, it is a feature ofthe invention as it is practiced in conjunction with an acetyleneabsorber that no additional diacetylene removal step need be practicedanywhere else in the process.

The temperature in the reflux drum is maintained at approximately 105 F.in this embodiment in which reflux is passed by way of pipe 24 intostripper 17 to regulate the operation therein. Bottoms in the stripperare reboiled and maintained at approximately 198 F., the pressure beingabout 108 mm. mercury. Under these conditions the bottoms aresubstantially denuded solvent, dimethylformamide, which is passed by wayof pipe 25, heat exchanger 35, pump 26, and pipe 27 to the acetyleneutilization as desired.

absorber which, as noted, is not shown. When desired cooling water canbe introduced into direct contact with the overhead leaving the top ofstripper 17 and, when introduced, is introduced by way of pipe 28,collected on trays 29 and removed by way of pipe 30.

Referring now to Figure 2 of the drawing, acetylenecontaining gas ofcomposition as shown in column l of Table II which in this embodiment isa gas from a deoiling absorber in which higher boiling or oily materialis removed from an acetylene-containing gas obtained by cracking ofhydrocarbons, is passed by pipe 40, refrigerator 41 and pipe 42 intowater absorber 43 wherein it is contacted with cold dimethylformamide(at a temperature below 0 F.) fed to the top of absorber 43 by way ofpipe 44. As described in connection with the description of Figure l, aportion of the solvent is passed by way of pipe 45 into pipe 40 toincrease the efficiency of the operation. The gas from the deoilerabsorber (not shown) is pumped at a temperature of approximately 40 F.and a pressure of about 55 pounds per square inch absolute intoadmixture with the solvent fed to pipe 40 by way of pipe 45 and isrefrigerated in refrigerator 41 to a temperature of approximately 25 F.which is the temperature at which the foot of water absorber 43 ismaintained. Bottoms from absorber 43, which is maintained atapproximately 49.6 pounds per square inch absolute, are passed by way ofpipe 46, heat exchanger 47, and pipe 48 into water stripper tower 49.Stripper 49 is maintained at sub-atmospheric pressure, the foot of thetower being held at a temperature near 198 F. and corresponding to apressure of 108 mm. of mercury. The bottom of tower 49 is heated byremoving a portion of the bottoms therein by way of pipe 50, reboiler 51and returning same by way of pipe 52. Bottoms from tower 49 arewithdrawn by way of pipe 53 and pumped by way of pump 54, pipe 55, heatexchanger 47, and pipe 56 to pipe 44 for introduction into absorber 43.Make-up dimethylformamide, as desired, can be fed to the system by wayof pipe 57. Also, as desired, at least a portion of the solvent can beremoved from the system by way of pipe 58 for regeneration orpurification purposes. Overhead from absorber 43 is passed by way ofpipe 59 into acetylene absorber 60 which is maintained at approximately44 pounds per square inch absolute. It will be noticed thatsubstantially all of the acetylene contained in the gas fed to absorber43 is taken olf as overhead by way of pipe 59- Please see columns 1 and2 of Table II. The temperature at the top of acetylene absorber 60 ismaintained at approximately 25 F. whereas the bottom of this absorber ismaintained at approximately -5 F. Bottoms are removed from absorber 60by way of pipe 61 and will contain almost all of the acetylene fed tothis absorber as can be noted from a comparison of columns`2 and 4 ofthe table. The bottoms which are withdrawn by way of pipe 61 arestripped of acetylene in an acetylene strippen-not shown, cooled andreturned to absorber 60 by way of pipe 62 for reuse and for this purposeare passed by way of heat exchanger 63, pipe 64 and refrigerator 65 intopipe 66 and finally into absorber 60. Overheadfrom absorber 60 is passedby way of pipe 67 through heat exchanger 63 and pipe 68 to It will benoted that the gas in pipe 68 contains only a negligible quantity ofacetylene, yet contains substantially all of the ethylene originallypresent, please see columns 1 and 3 of Table Il. The internalconstruction of absorber 43 as will be understood by one skilled in theart in possession of this disclosure is such that the relatively smallquantity of dimethylformamide is intimately contacted with the gasestherein. By operating the combination of the embodiment of Figure 2, asdescribed, the invention permits a simplified operation to obtain adehydrated and deacetylized ethylene-containing gasv in a simplifiedmanner, as will be readily understood by those skilled in the art inpossession of this disclosure.

TABLE I Material Balance-Mols per stream day column Number 1 2 a 4 5 6 7s 9 Pipe Number 1 6 10 14 22 27 9 7 8 The injection of Solvent ahead ofthe refrigerator 41 in relatively low pressure compared with thepressures com- Figure 2 considerably reduces the freezing point of themonly employed when dehydrating gases by means of resulting mixture,which when it contains equimolar pro- 2 0 glycols.

portions of dimethylformamide and water will have a The use ofdimethylformamide according to this invenfreezing point as low asapproximately 68 F. and will tion, to dehydrate hydrocarbon-containinggases, without have a viscosity of onlyva few centipoises. Thus,disubstantially removing therefrom desirable hydrocarbonsmethylformamide has been found to be ideally suited r or even acetylene,is a noteworthy improvement. to drying operations for producingexceptionally low dew 2 The water content of the dimethylformamide whichis points `or the quantitative removal `of water from gases removed fromthe foot of the water absorber will be sufsuch as hydrocarbon gases orgases containing hydrocarciently high to avoid absorbing acetyleneand/or ethylene bons. in substantial quantity but will be insuflicientto prevent When the embodiment of Figure 2 is employed, it will removalof water from the gas stream, thus resulting in be noted that theenthalpy (refrigeration) requirement the control which 'this inventionsets forth can be exervery closely approaches the minimum when theminimum cised. Thus, it is clear that a hydrocarbon gas-rich diis takenas only the latent heat of vaporization of water'. methylformamide, asfrom an acetylene absorber, or sub Less refrigeration is required thanwith conventional stantially pure dimethyl-formamide, can be passed intothe bauxite drying. Y top of the dehydrator column' to remove Water fromgases The use of dimethylformamide at temperatures below fed thereto,also containing acetylene and ethylene, yet by 32 F. as in theembodiment according to Figure 2, rethe time the solvent is removed asbottoms, its water consults in several important advantages, one ofwhich is, Vtent will have increased and it will contain only a very asnoted, that an extremely low dew point is obtained so "small ornegligible proportion of feed gases other than that the gas issuflciently dry` for subsequent treatment water vapor. to removeacetylene, also at rather low temperatures, for 4,0 Usually thedirnethylforrnamide as fed to the dehyexample, as described and claimedin- Serial Number drato'r column will vbe substantially water-freealthough 441,809, tiled July 7, 1954, by the present inventor. it cancontain an appreciable concentration of water if the TABLE n Y Materialbalance- Mols per streani day 061m Number 1 2 f3 4 5 6 7 Pipe Number 4059 68 61 y6 2 48 56 Hydrogen Nitrogen Carbon Monoxide-- MethaneAcety1ene. Ethylene- Ethane Carbon Dioxide.. Methyl Acetylee Propylenater-'.- DMF y ',lt is advantageous to directly remove as much water as60 water content ofthe feed gas is relatively low. The water can beremovedY conveniently prior to the dehydration content of the'solventleaving the water absorber is prefstep by such direct means as quenchingand prechilling. erably within the range14 tor 50mole percent, although,This precaution mlnimlzesthe amount of heat of conden- ,Operationoutside thisy range is not excluded The desation 0f Water t0 be removed1D a 165s direct manner by hydrator, according to this invention, canbeoperated at the abSAOPtiV drying Stell When P-fechiuillg is cafred .f5.5temperatures within the approximate range of to 100 .wafefflgefaftlon'tempefatufe ,levffl as 1n Ffgil'e 2f 1t 1S rF., the low temperaturesbeing presently preferred as evi- 905,5-1b1e to dehydrate Wlth a, mlmmumof dlmethylffxm" dent vfromthe advtantages of lower dew point, etc. asapamldesoivent- As a mgmt m thef embdment of Elgure parent from thisdisclosure.- The pressure in the dehy- 2, the ratlo of water todlrnethylformamide 1n the bottoms dr t u, .11b t h v h, h from absorber43 is near one toone. As a consequence v70 a or z onusuaywl e a mosp encpressumor Lg er `ofj both low solvent rate and water dilution, theamount of preferably approlmately Same ,pressure Level as the ,acetyleneand other hydrocarbons' dissolved in the ab- .acetylenet-@bsofpilonSteP- i Y "Sol-ber exit liquid isnegligib1ey A The invention isparticularly applicable to feed stocks Another advantage, it will benoted, is Vthat the drying which have been used in the examples ofFigures 1 and 2 operation of the present` invention can be conductedlata tlieserleed,stockslpreferably will be rsulfur-free, that is,

asma/9 sion of this disclosure that the said proportion will have to besuch that additional water can be absorbed under.

the prevailing conditions and after absorption of said additional watersufficient to prevent absorbing and/or retaining absorbed an undesiredproportion of hydrocarbon. Thus, it is clear that under the conditionsof contact of the gas and the dimethylformamide solvent, the solventshould have an affinity for water.

An inherent advantage of this dehydration process is that the dehydratortower may function as a heat exchanger, employing countercurrent directcontacting of vapor and liquid. In the example of Figure 1, theacetylene containing gas enters the dehydrator at 100 F. and leaves at 9F. being chilled by exchange with the cold solvent. Still anotherinherent advantage evidenced in Fig. l is that the hydrocarbon fogassociated with acetylene production tends to deposit out in thedehydrator tower as the gas stream is progressively chilled. A largeamount of tars can thus deposit out, especially when the contacting isin a baffled section, without interfering with the operation. Bycontrast, it takes very little tars depositing on silica gel or bauxitedrying beds to cause interference and even plugging of the bed asalready noted. Reasonable variation and modification are possible Withinthe scope of the foregoing disclosure, drawing, and the appended claimsto the invention, the essence of which is that dimethylformamide hasbeen found to be excellently suitable for the dehydration of gasescontaining hydrocarbons, especially hydrocarbon gases containingacetylene and/or ethylene and that certain modus operandi based uponthis contribution have been contributed also.

I claim:

1. A method for dehydrating a hydrocarbon gas containing acetylene whichcomprises contacting said gas with a dehydrating solvent consistingessentially of dimethylformamide, continuing the contacting of said gaswith said dimethylformamide, and separating said dimethylformamide fromsaid gas when it contains from about 14 to 50 mol percent of water at atemperature below F.

2. A method for the dehydration of a gas containing hydrocarbonsincluding acetylene and for the removal of acetylene from said gas whichcomprises contacting in a dehydration zone said gas withdimethylformamide solvent containing acetylene obtained as hereafterdescribed in a proportion of said solvent to said gas such that said gaswill be dehydrated under the conditions of contact, recovering from saidzone a dehydrated gas, contacting said dehydrated gas withdimethylformamide in an acetylene absorption zone under conditions toabsorb acetylene therefrom, thus obtaining said solvent containingacetylene and returning at least a portion of said solvent as said'solvent containing acetylene to said dehydration zione.

A method according to claim 2 wherein the solvent containing water isremoved from the dehydration zone, is stripped of water and passed tosaid acetylene absorption zone as at least a portion of the solventemployed therein.

4. A method for the removal of water from a hydrocarbon gas containingacetylene to dehydrate said gas which comprises contacting said gas withdimethylformamide, continuing the contacting of said gas with saiddimethylforrnamide until the latter contains at least approximately 14mol percent of water and then separating said dimethylformamide fromsaid gas.

5. The dehydration of a gas containing acetylene which comprisescontacting said gases with dirnethylformamide in a proportion and underconditions such that itwill contain `before separation from said gases aquantity of water amounting to at least 14 mol percent of water at 0 F.,stripping water from the dimethylformamide thus obtained and thenemploying said dimethylformamide to remove at least one component ofsaid gas stream, which has been dehydrated, therefrom.

6. A method for dehydrating a gas containing acetylene, ethylene, andother gases which comprises admixingsaid gas with a substantial quantityof dimethylformamide containing water in a quantity suicient to lowerthe freezing point of the mixture to a temperature below about 0 F.,then chilling the mixture thus obtained to a temperature below 0 F., butabove its freezing point, contacting said mixture with additionalquantities of dimethylformamide in proportion and under conditions atsaid temperature such that said gas in said mixture will besubstantially dehydrated, recovering a dehydrated gas anddimethylforrnamide containing from 14 to 50 mol percent water, heatingsaid dimethylformamide to expel water therefrom, and returning the`dehydrated dimethylformamide for reuse, passing the dehydrated gasesobtained as above described into contact with additional quantities ofdimethylformamide at a temperature below about 0 F., in the absence ofwater, to remove therefrom substantially all of the acetylene containedtherein, and recovering the acetylene from said last mentioneddimethylformamide as a product of the process.

7. A method according to claim 6 wherein ethylene substantially freefrom acetylene is recovered as a product of the process.

8. A method for dehydrating a sulfur-free gas containing hydrocarbonswhich comprises contacting said gas with a minor proportion ofdimethylformamide containing water in a proportion suicient to renderthe hydrocarbon content of the gas substantially insoluble in saiddimethylformamide except for an amount of the order of 0.37 mol percentbut insufficient to prevent absorption of water from said gas under theconditions of contact.

9. A method for dehydrating a gas containing hydrocarbons whichcomprises contacting said gas with dimethylformamide containingacetylene under conditions so as to absorb water therefrom and to resultin dimethylformamide containing water in a proportion suicient to renderthe hydrocarbon content of the gas substantially insoluble in saiddimethylformamide except for an amount of the order of 0.37 mol percentbut insufficient to prevent absorption of water from said gas under thecon,- ditions of contact and then separating said dimethylformamide`from said gas.

10. A method for dehydrating a hydrocarbon gas containing acetylenewhich comprises contacting said gas with a dimethylformamide dehydratingsolvent containing acetylene, continuing the contacting of saiddimethylforrnamide solvent with said gas until it contains from about 14to 50 mol percent of water at a temperature below 0 F., and thereafterseparating said resulting dimethylformamide solvent from said gas.

l1. A method for the removal of water from a hydrocarbon gas containingacetylene to dehydrate said gas which comprises contacting said gas withdimethylformamide containing a minor proportion of acetylene, continuingthe contacting of said gas with said dimethylformamide until saiddimethylformamide contains at least approximately 14 mol percent ofwater and then separating 'said dimethylformamide `from said gas.

Vamide contains at least 14 mol percent of water and then separatingsaid dimethylformamide from said gas. 1.3. In a low-temperature solventextraction process wherein a hydrocarbon gas which contains acetyleneand moisture and which is at an elevated temperature is contacted withdimethylforrnamide solvent at a low temperature and then acetylene isseparated and recovered from the -dimethylformamide solvent having theacetylene ab# sorbed therein, the improvement which co-mprisescontacting the hydrocarbon gas containing acetylene before removal ofsaid acetylene from said hydrocarbon gas with dimethylformamide solventwhich contains acetylene and which Was recovered from the a-cetyleneabsorption step to thereby remove the moisture from said gas and coolthe said hydrocarbon gas `containing acetylene which is to be contactedin the low-temperature solvent extraction process.

14. A method for dehydrating a hydrocarbon gas containing acetylene andwater which lcomprises contacting said gas with a dimethylformamidedehydrating solvent containing from about 14 to 50 mol percent of waterat a temperature below 0 F. and thereafter separating said solvent fromsaid gas.

15. A method for dehydrating a gas containing hydrocarbons whichcomprises providing an absorbent consisting essentially ofdimethylformamide and Water by adjusting the amount of water in thedimethylformamide to be such that hydrocarbon will not dissolve thereinto an extent greater than of the order of 0.37 mol percent and thequantity of water in the dimethylformamide to be less than that requiredto saturate the same and when the Water content of thedirnethylformamide has been so adjusted then contacting said gascontaining hydrocarbons that also contains Water with saiddimethylformamide in which the Water content has been adjusted asstated, and thereafter separating said dimethylformarnide from said gas`containing hydrocarbons and recovering said gas containing hydrocarbonsin substantially dehydrated condition.

Dimethyl Formamide Product Information, Grasselli Chemicals Department,Du Pont Co., page l thereof.

14. A METHOD FOR DEHYDRATING A HYDROCARBON GAS CONTAINING ACETYLENE ANDWATER WHICH COMPRISES CONTACTING SAID GAS WITH A DIMETHYLFORMAMIDEDEHYDRATING SOLVENT CONTAINING FROM ABOUT 14 TO 50 MOL PERCENT OF WATERAT A TEMPERATURE BELOW 0* F. AND THEREAFTER SEPARATING SAID SOLVENT FROMSAID GAS.